Grain aeration systems and techniques

ABSTRACT

In one embodiment, the invention is directed toward a networked grain aeration control system. For example, the system can provide centralized monitoring of the aeration of a number of grain storage facilities, thereby improving the management of stored grain. The networked grain aeration control system can allow the custodian of the system to offer an aeration service. Farmers, or other individuals, cooperatives, or companies can purchase the aeration service at a cost proportionate to the amount of stored grain to be aerated and the duration of storage. In this manner, the purchaser of the aeration service can avoid relatively high fixed costs that can be associated with various aeration hardware.

[0001] This patent application claims priority to U.S. ProvisionalApplication No. 60/311,752, filed Aug. 10, 2001. The entire content ofU.S. Provisional Application No. 60/311,752 is hereby incorporated byreference.

FIELD

[0002] The invention relates to the agricultural industry and, moreparticularly, to aeration systems for stored grain or other crops.

BACKGROUND

[0003] Agricultural crops, such as harvested grain, are often stored ingrain storage facilities, such as grain bins, which are usuallyclustered at various geographic sites. For example, individual farmers,cooperatives, or corporations often store grain after the grain isharvested in hopes that the market price will increase. In addition,purchasers often store the grain for periods of time, prior to milling,shelling, or other processing of the grain.

[0004] Aeration systems and techniques have been developed to aeratestored grain with the primary purpose of preventing spoilage from insectand microbial activity. In addition, aeration can be used to achieve orapproach a desired temperature and/or a desired moisture content forstored grain to increase its usability. Aeration can maintain, and insome cases, improve the quality of stored grain by achieving specifiedtargets for temperature and moisture content, allowing sellers toreceive higher prices for the grain, and allowing purchasers to maintainor improve the quality of grain that was purchased.

SUMMARY

[0005] In one embodiment, the invention is directed to a networked grainaeration control system. For example, the system can provide centralizedhigh-level control and logging capabilities for the aeration of a numberof grain storage facilities located at a number of different sites,thereby improving the management of stored grain. A networked grainaeration control system enables the custodian of the system to offer anaeration service to multiple grain storage customers. Using thenetworked grain aeration control system, the custodian can providecustomized configurations and strategies for a local controller from acentralized remote location, as well as log aeration operation and otherinformation such as weather data originating at different sites.

[0006] Farmers, or other agricultural producers, cooperatives, orcompanies can purchase the aeration service at a cost proportionate tothe amount of stored grain to be aerated and the duration of storage. Inthis manner, the purchaser of the aeration service can avoid the fixedcosts associated with stand-alone controllers . In addition, the sellerof the service can regulate and meter the usage of the grain aerationtechnology.

[0007] In one embodiment, a networked grain aeration system includes afirst controller coupled to a first sensor and a first aeration fanpositioned in proximity to a first agricultural crop storage facilitylocated at a first site, wherein the first controller controls theoperation of the first aeration fan according to conditions sensed bythe first sensor. The first sensor may be one of a first set of sensorscoupled to the first controller located at the first site. In that case,the first controller can control the operation of the first aerationfan, and possibly additional fans positioned in proximity to additionalcrop storage facilities at the first site according to conditions sensedby the first set of sensors. The first controller provides tailoredcontrol to the first fan so the grain in the first facility is managedindependently of other facilities at the site.

[0008] The system may also include a second controller coupled to asecond sensor and a second aeration fan positioned in proximity to asecond agricultural crop storage facility located at a second site,wherein the second controller controls the operation of the secondaeration fan, and possibly additional fans positioned in proximity toadditional crop storage facilities at a second site according toconditions sensed by the second sensor. The second sensor may be one ofa second set of sensors coupled to the second controller located at thesecond site. Each facility at the second site can be managedindependently of other facilities at the second site and otherfacilities at other sites. The system may also include a centralcomputer communicatively coupled to the first and second controllers,wherein the central computer oversees, monitors and records operationaldata relating to the aeration at both the first and second agriculturalcrop storage facilities. In particular, the central computer may log ahistory of sensed conditions, run time of the aeration fans, sensedconditions during the run times, and possibly other operationalparameters used by the controllers.

[0009] The central computer may provide tailored configurations andstrategies on a timely basis to the first and second controllers toimprove the performance of the local controllers. Although instructionsto each controller may be generated specifically with the grain in therespective facility in mind, the accumulated experience from allfacilities at all sites may be considered to refine control parametersand strategies delivered to each facility.

[0010] The first and second sensors may be temperature sensors, relativehumidity sensors, barometric sensors, or sensors having some combinationof temperature, barometric, and relative humidity sensing functionality,although the invention is not necessarily limited in those respects. Therespective controllers can use conditions sensed by each of the sensorsto identify appropriate run times for the aeration fans. In some cases,multiple (redundant) sensors are used by each respective aerationcontroller. In that case, diagnostic steps may be performed to assurethe sensed values are valid or to provide continued operation when onesensor may fail.

[0011] The agricultural crop storage facilities may be grain storagebins or other structures such as silos, bunkers, flat storages, ortanks. The central computer can be communicatively coupled to the firstand second controllers located at the first and second sitesrespectively via a network, such as a packet based local area network,wide area network, or global network such as the, Internet, or a publicswitching telephone network (PSTN). The communication links may be wiredor wireless. In some instances, a site may be segregated into two ormore subsets, each with a local controller that operates independentlyof each other. Each local controller may be communicatively linked tothe central computer to accommodate a number of circumstances. Thesecircumstances may include local network interferences, physical barrierssuch as railroad tracks, and electrical power distribution that may comefrom more than one source.

[0012] The central computer may receive cumulative data from each localcontroller, and can parse, validate, store, and possibly organize dataincluding data sensed by the various sensors. For example, weatherinformation can be a valuable commodity that is gathered by the varioussensors, particularly when a large number of sensors are geographicallydistributed. This weather data may be sold and/or used, for example, toimprove weather prediction or even improve the ability to identify stormwarnings such as tornado warnings. In addition, information relating tothe operation time of the various fans can also be collected and storedby the central computer to help monitor system operation. The centralcomputer may create records that represent, for example, an aerationhistory for a particular lot of grain. These records could provideassurance as to the conditions the grain experienced during the entireperiod from harvest to consumption. For instance, these records couldreflect whether or not a condensing situation occurred that might fosterinsect or microbial activity occurred during the span of storage.Recorded operational parameters can be used to document the aeration ofa lot of grain, and may provide useful backup that can be downloaded toa replacement controller, e.g., in the event of controller malfunction,destruction, or failure.

[0013] One or more client computers may also be communicatively coupledto the central computer. For example, farmers or other purchasers of theaeration service may use client computers to access information relatingto their grain and the aeration service provided for that grain, e.g.,via a web browser interface. Each individual client computer may haveaccess only to the data that pertains to that particular client, i.e.,the purchaser of the service. In other words, a first client computermay not have access to data pertaining to a second agricultural cropstorage facility, and likewise, the second client computer may not haveaccess to data pertaining to the first agricultural crop storagefacility. Password protection and/or other security and authenticationmethods may be used to enable specific data delivery to the respectiveclient computers.

[0014] The system may utilize one or more algorithms to ensure thataeration is performed at the desired times and under the appropriatecircumstances. As one example, the present inventor has developedmethods for aeration of stored grain as described in U.S. Pat. Nos.4,688,332 and 4,522,335, which are hereby incorporated by reference intheir entireties. Improvements on the methods of the aforementionedpatents, however, can also be implemented. For example, an aerationmethod may take into account other variables, in addition to ambientconditions to achieve better aeration results. Also, improvements to thetechniques described in the above-identified patents may also be used,such as truncation of temperature bands or relative humidity bands forimproved results in certain climates. In some cases, the truncation canbe performed dynamically based on sensed data during recent accumulationof fan operation or a climate history during past seasons. Suchimprovements are described in greater detail below. The functions of theaforementioned patents and improvements to them can be executed at thelocal controllers to provide real-time capability. The central computercan download configuration files or other instructions from time to timein response to accumulated data from each local controller so personnelemployed for other duties at a grain storage site do not have to beskilled in grain aeration management.

[0015] Another variable that could be taken into account in a networkedaeration system, or even in a more conventional non-networked grainaeration unit, is heat produced by the aeration fan itself. For example,aeration fans can give off heat from the motor, and more notably,aeration fans may generate significant amounts of heat via frictionbetween the fan blades and the air. An aeration method or algorithmaccording to the invention may account for heat produced by operation ofthe aeration fan to yield better aeration results.

[0016] In one case, an aeration method makes an adjustment to sensedconditions to account for fan size and the size of the grain storagefacility. For example, given the fan size and the size of the grainstorage facility and its current contents, a theoretical offset ofsensed ambient temperature could be calculated. In other words, theoffset can represent the difference between the ambient air temperatureand the temperature of the air after it has passed through the aerationfan. Accordingly, the offset can account for heat produced by the fan,and can be used to more accurately select appropriate ambient air toforce through the grain so various targets may be achieved.

[0017] If used to modify the adaptive algorithm incorporated in theaforementioned patents, this offset would have the effect of shiftingthe starting point for a series of calculations to establish ranges ofacceptable ambient conditions for current aeration. This modification tothe targeted temperature (the ambient air average temperature or suchadjusted) could be accomplished by subtracting the calculated offsetfrom such targeted temperature. In turn, the sensed ambient relativehumidity would need to be adjusted using psychometric formulas to adjustfor the raised temperature. This method may be used in positive pressureaeration systems and not in negative pressure aeration systems.

[0018] Additionally, the method may account for static pressure withinthe facility, e.g., at the location of an aeration fan or after the fanand prior to air entry into the grain. For example, the amount of staticpressure may be related to how full the facility is, relative to itscapacity. Because the amount of grain in a facility may change often, byaccounting for static pressure, a better approximation of the offset canbe achieved because the heat generated from the friction on the fanblade may be higher if static pressure is higher and may be lower ifstatic pressure is lower. If a static pressure sensor were employed, theoffset utilized in the above method could be calculated directly ratherthan theoretically.

[0019] In one particular case, which can be used in positive pressureaeration systems, a feedback sensor, e.g., a feedback node (f-Node), isused to measure the actual temperature and/or relative humidity (RH) ofair after it has gone through the fan. The use of the f-node can achievean actual measurement of the temperature offset and/or RH offset causedby the operation of the aeration fan. The measured offset can then beused as feedback to the aeration controller. The aeration controller canthen control the operation of the fans accordingly, accounting for bothambient conditions and the offset of air conditions relative to theambient conditions caused by fan operation. In general, ambient air withlower temperature and a higher relative humidity would need to beselected by the controller to achieve the desired targets since heatingair lowers relative humidity.

[0020] In accordance with the principles of the invention, a centralcomputer may log the data received from the f-node to supplement therecord from other sensors to improve the reliability of modeling theconditions within the storage facility over a span of time. For example,this data could be used to demonstrate that the grain stored inside thestorage facility was never exposed to conditions favorable for insectactivity or the growth of microbes including fungus that can producemycotoxins, allergens, or other conditions that may result in graincontamination. The documentation could increase the value of the grainand justify the added cost of an f-node sensor because of increasedconfidence in the safety of the grain, whether intended for human oranimal consumption.

[0021] Another improvement to grain aeration management that can beprovided by a networked system is electricity conservation and costreduction. With a networked system, contracts may be negotiated withsuppliers of power to grain storage operations to shed certain loads inhigh demand periods in order to obtain lower rates. The total horsepowerof aeration fans deployed at a grain storage site on one or morefacilities may range from just a few to several hundred, to more than athousand. The total in the USA is estimated at 7,000,000 horsepower.Since a fan should not be turned off with certain conditions existing inthe grain, load interruption can only be accomplished with fullknowledge of the state of each grain facility or loss may result.However, conventional aeration fans are often operated manually morethan necessary to be on the safe side because of a lack of informationand skill regarding aeration practice.

[0022] A networked system could provide the necessary expertise to makethat decision and to communicate with various power companies in realtime regarding their current load factor. If need be, the networkedaeration system could accommodate requests for short duration shutdownsof operating fans to relieve power suppliers during peak demand periods.A networked system may have sufficient information and expertise tosafely manage fan operation around the competing goals of preventingspoilage, modifying moisture content, and economizing on electricityconsumption, especially at certain times. In addition, a load queuingscheme may be employed at each grain storage site so the totalhorsepower of the fans in operation at one time does not exceed specificlevels for that site, or while certain other high load demands may be inuse. Any such implementation may balance the respective considerationsof the condition of the grain, the targets set for the grain, theweather and season and the cost of electricity and the extra charges ofexceeding a specified demand.

[0023] The invention can provide a number of advantages. For example,improved aeration techniques can assure minimum or no deterioration, andmay actually improve the quality of stored grain. Indeed, aeration canhelp ensure that fungus producing mycotoxins, some of which can becarcinogenic, cannot live or flourish in the aerated grain. At aminimum, the aeration can ensure that mycotoxin levels, allergen levelsand other contaminate levels do not increase during storage, andtherefore, can help ensure that contaminant levels within the storedgrain are kept below acceptable levels.

[0024] Acceptable levels of contaminants, however, may correlate tosmaller and smaller amounts of contaminants per unit of grain asresearch on the effects of contaminants continues to advance. Inaddition, aeration can be effective in avoiding the loss of all of thegrain in a facility to spoilage, the spoiling of a portion of grain withthe resulting contamination of unspoiled portions of grain within afacility due to mixing when removing the contents, preserving grainweight by eliminating the typical shrink due to moisture loss withmanual operation of aeration, minimizing insect infestation, achievingtargeted moisture content levels, achieving uniformity of kernel tokernel moisture content, re-hydrating of over-dry grain, and drying ofover-wet grain within the limits of airflow availability. In addition,with grain storage facilities with adequate aeration systems that areappropriately managed, upstream practices of high heat drying may beeliminated or modified. This reduction in harsh treatment of grain canreduce stress cracks and the subsequent breakage during handling as wellas evaporation of certain volatiles from the grain. The entire networksystem can work toward generally preserving and possibly improving thequality of stored grain. For these reasons, precisely managed andcontrolled aeration may become an integral part of future grain storage.

[0025] Networked grain aeration also provides advantages in terms ofaccessibility of the data that is accumulated. For example, purchasersof the aeration service may be able to access data from remote computersconnected to the Internet. In other words, farmers can have access todata that shows them results of the service they are receiving. Inparticular, farmers, or others can have access to data that tracks theconditions surrounding the stored grain, and the various aerationmeasures taken on that grain. Such data can provide a history of storedgrain, allowing for trace ability and improved accountability of thestored grain. Even a chain of custody may be established and documented,in some cases, allowing the custodian of the grain to provide assurancesof safety.

[0026] In one implementation of the invention, a chain of custody isautomatically documented in the centralized computer of the networkedaeration system. The documentation can even be uploaded from the localcontroller or downloaded from the central server, for example, todelivery vehicles, when the stored grain is moved from a given storagefacility. For example, purchasers of the grain may desire informationdescribing the history of a particular lot of grain being purchased. Byallowing this information to be uploaded from computers at the storagefacility to accompany the grain during transportation or to be availableby other means at the point of delivery, verification for propersegregation at the next point of delivery may be enabled. In addition,if the grain merchandiser (such as a country elevator) also subscribesto the networked aeration service, he not only has assurance of thequality of a lot of grain before co-mingling with other lots of grain,but he can segregate lots of grain according to very high resolutionfactors not previously available. Additionally, the grain merchandisercould schedule deliveries originating from many different producers to acertain destination at a given time to assemble larger lots of grainwith highly consistent attributes that best meet his customer's needs.

[0027] Purchasers of grain and the end user (the public) can be morereadily assured of the safety of the purchased grain or productsprocessed from grain or meat, milk, and eggs from livestock because ofthe detailed records and chain of custody enabled with a networkedaeration system.

[0028] Centralized control and monitoring can also improve the level ofaeration quality, allowing the provider of the aeration service tocentrally monitor whether the individual aeration units are workingproperly. Another advantage of networked grain aeration includes theability to provide more effective control of aeration in variousgeographically distributed grain storage units. In other words, insteadof a local grain storage manager controlling aeration as he or she seesfit, centralized expertise can be used to monitor and more effectivelycontrol aeration. In addition, if device failure occurs, centralizedrecord keeping can allow information relating to recent climate andaeration fan operation to be downloaded to a new controller that may beinstalled following failure of a previous controller.

[0029] Networked grain aeration may also allow for a new and inventivepricing arrangement that can be attractive to prospective purchasers. Inone embodiment, the invention may comprise a method that includesmonitoring aeration fans positioned in remotely located agriculturalcrop storage facilities via a central computer of a networked grainaeration system, and charging fees related to an amount of grain and/ora span of time it is being stored in any given agricultural crop storagefacility.

[0030] Farmers, cooperatives or other individuals or companies that areprospective purchasers of aeration control systems may be reluctant toinvest in aeration control hardware. For example, farmers may not wantto spend the fixed costs, given the unknowns associated with weather andcrop yield for any given year as well as marketing decisions. Theinvention can allow the seller of aeration control service to bear thefixed cost, and sell the aeration service at costs related to the amountof aeration service that is actually utilized. In this manner, thecharge for the aeration service may reflect the amount of grain beingaerated, and the time for which the grain is actually stored andaerated, which may vary. This method also overcomes a “free-rider”problem, wherein a purchaser of an aeration unit for a small storagefacility uses the aeration unit in a much larger facility or formultiple facilities. Such applications lower initial investments, butdeliver overall results that are deficient from those expected from arobust system.

[0031] In another method, the invention may include monitoring aerationfans positioned in remotely located agricultural crop storage facilitiesvia a central computer of a networked grain aeration system and sellinggrain spoilage insurance for an amount of grain being stored in anygiven agricultural crop storage facility. Networked grain aeration canfacilitate the ability to guarantee against grain spoilage. Farmers maybe able to take out loans from a bank, based on the amount of harvestedcrops the farmer owns but has not yet sold. However, the banks maydesire, or even require the grain spoilage insurance to protect theirinvestments. The seller of aeration services, utilizing networked grainaeration having centralized control, may be able to provide thisinsurance because the centralized control allows the seller of theservice to adequately manage against grain spoilage and thereby protectthe grain assets and keep premiums affordable. Currently, grain storageoperations are burdened with the entire risk of spoilage, since noinsurance is available because of the difficulty of determiningappropriate and affordable premiums due to the haphazard methods ofcurrent grain storage practice and lack of record keeping.

[0032] Additional details of these and other embodiments are set forthin the accompanying drawings and the description below. Other features,objects and advantages will become apparent from the description anddrawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1 is a block diagram of an exemplary networked grain aerationsystem.

[0034]FIG. 2 is a conceptual diagram of an agricultural storage facilitymaking use of a networked grain aeration system.

[0035]FIG. 3 is an exemplary block diagram of one embodiment of grainaeration system that can be installed in at a storage facility.

[0036] FIGS. 4-12 are flow diagrams illustrating techniques according tovarious embodiments of the invention.

DETAILED DESCRIPTION

[0037] The invention is directed to a networked grain aeration controlsystem, various grain aeration techniques, pricing schemes for a grainaeration service, and other techniques that can improve grain aerationand the aeration service. Using the system and/or techniques can improvethe usefulness of stored grain. In this disclosure, the term grainrefers broadly to any harvested crop of seeds, including rough and smallgrains, maize, legumes, pulses or any other harvested agricultural cropthat is customarily stored in bulk and that can benefit from aeration.

[0038]FIG. 1 is a block diagram of an exemplary networked grain aerationsystem 10. For example, system 10 can provide centralized control,monitoring and/or historical logs of the aeration of grain in a numberof grain storage facilities 12. Any number of grain storage facilitiesmay be included in system 10. However, for simplicity, only twofacilities 12A and 12N are illustrated in FIG. 1. System 10 may improvethe ability to manage the aeration of stored grain. Moreover, networkedgrain aeration system 10 can allow the custodian of the system 10 tooffer an aeration service to multiple grain storage facilities viaunique pricing arrangements.

[0039] As shown in FIG. 1, networked grain aeration system 10 includestwo or more grain storage facilities 12. Each grain storage facility 12can be equipped with an aeration fan 13 that is controlled by arespective aeration controller 14. For example, each aeration controller14 may comprise a computer controller that causes the respectiveaeration fan 13 to turn on at times when effective aeration can occur.For example, aeration controller may control aeration fan 13 by invokinga control node as described below with reference to FIG. 3. In any case,one or more sensors 16 may be coupled to each respective aerationcontroller 14 to provide measurements of ambient conditions andmeasurements associated with the stored grain. The measured conditionsmay be used by aeration controller 14 to determine when to turn on therespective aeration fan 13.

[0040] Sensors 16, for example, may include temperature sensors andrelative humidity sensors. Separate temperature and relative humiditysensors may be used at each storage facility 12, or a sensor having bothtemperature and relative humidity sensing capabilities can be used. Inaddition, various other sensors such as temperature sensors positionedto measure the temperature of the stored grain, sensors to measurebarometric pressure, sensors to measure static pressure within thestorage facility, or feedback sensors that account for heat produced bythe operation of aeration fans 13 may also be used. Additional detailsof these and other sensors are provided in greater detail below. In anycase, aeration controller 14 controls aeration fans 13 based on sensedconditions and various input parameters to achieve a desired temperatureand moisture content of the stored grain, with or without a deadline.

[0041] For example, aeration controller 14 may execute one or moreaeration techniques such as those described in U.S. Pat. Nos. 4,688,332and 4,522,335. U.S. Pat. Nos. 4,688,332 and 4,522,335 are incorporatedby reference in their entireties. In particular, aeration controller 14may receive input specifying a desired moisture content for the storedgrain. The controller may calculate a desired temperature best for thatgeographic location, or such desired temperature may be modified byinput in specific cases.- Aeration controller 14 may define atemperature band and a relative humidity band respectively around thedesired temperature and a relative humidity that corresponds to thedesired moisture content for a given temperature. For example, if thedesired temperature is 48 degrees Fahrenheit, aeration controller 14 maydefine a temperature band of ±2 degrees, i.e., 46 degrees to 50 degrees.Similarly, aeration controller 14 may define a relative humidity band of±2 percent.

[0042] The temperature band may depend on beginning grain temperature,or may simply be a band defined about a target temperature determined inanother method for the grain. In one example, the target temperature isdetermined by an average temperature over a span of time, e.g., in oneuseful ease, a twenty-one day moving average of ambient temperature.Aerating grain at or near its current temperature can help avoidmoisture migration in the stored grain. In other cases, the targettemperature can be offset to account for heat produced by aeration fan13, barometric pressure, extreme climate fluctuations, or othervariables. In addition, the target temperature may be dependent on thespecific type of grain to be aerated. Moreover, different targettemperatures may be selected based on whether re-wetting or drying isdesirable. The target temperature may also be offset from the averageduring extremely hot or extremely cold conditions or even in seasonalcases. The target temperature may also be adjusted to prepare the grainfor readiness for shipping if the destination is known or the grain willbe transported through a different climate. As an example, transportingcold grain through a tropical region by ship can result in severecondensation that encourages spoilage. Accordingly, in that case, thegrain may be warmed prior to transport.

[0043] The target relative humidity for a desired moisture content maybe temperature dependent and may also depend on the current temperatureof the grain. In addition, measurements of barometric pressure may beused to adjust the target relative humidity for a given temperature.Also, the target relative humidity may be dependent on the specific typeof grain to be aerated. Moreover, a different target relative humidityfor a given moisture content may be selected based on whether re-wettingor drying is to occur. The size of the bands may vary in differentimplementations.

[0044] If sensor 16 identifies an ambient temperature within thetemperature band, say 47 degrees Fahrenheit, aeration controller 14identifies the target relative humidity associated with the sensed 47degree temperature, e.g., 63 percent. In other words, the targetrelative humidity may depend on the current ambient temperature, andfurthermore, may also depend on the current temperature of the grain. Inany case, at 47 degrees, for example, if the ambient relative humidityis within the relative humidity band of say 61 percent to 65 percent (±2percent of 63 percent), then aeration controller 14 may activateaeration fan 13. Larger or smaller bands could also be defined. Inaddition, barometric pressure readings or other climate conditions couldbe used. In that case, aeration may occur only when the conditionssurrounding storage facility 12 fall within the defined climateconditions. Also, climate conditions, such as barometric pressure, forexample, may be used to adjust the temperature and/or relative humiditytargets and bands.

[0045] Aeration controller 14 may also have a regulator-like mechanismthat ensures that the aeration fan 13 can only run for an allottedamount of time, on average, in order to conserve power. For example,aeration controller 14 may budget an amount of time for a given timeinterval, e.g., four hours per day. In that case, aeration controller 14would activate aeration fan 13 for only four hours per day on average,even if the desired conditions of temperature and relative humidity werepresent for more than four hours per day.

[0046] Aeration controller 14 may also accumulate a backlog of time toaccount for unused time that was budgeted for aeration. Thus, if thedesired conditions were not present for two days, then twelve hours ofaccumulated budget may be used on the third day. In other words, thefour hour budgets for three days may accumulate to twelve hours, whichcan be used in succession once the desired conditions occur. Once theaccumulation of budgeted time is used, however, aeration fan 13 may beturned off even if the desired conditions are still present.

[0047] In addition, aeration controller 14 may define a backlogthreshold, say twenty hours (the equivalent of five days at four hoursof budget per day). If the backlog exceeds the threshold, aerationcontroller 14 may enlarge the temperature and/or relative humidity bandsto improve the likelihood that aeration will occur. This can help ensurethat at least some aeration occurs even if the ambient conditions aresub-optimal. The temperature and/or relative humidity bands may returnto the originally defined values once the backlog does not exceed thethreshold, or alternatively, the changed temperature and/or relativehumidity bands may be used for longer periods of time once the change isinvoked.

[0048] One extremely useful improvement to these aeration techniques mayinvolve the truncation of the temperature and/or relative humidity bandsto improve aeration for climate specific scenarios. In particular,aeration controller 14 may truncate the temperature and/or relativehumidity bands for different climate scenarios in a manner that causesaeration to achieve improved results in terms of more accuratelyachieving a target temperature and/or moisture content for the storedgrain.

[0049] For example, assuming a target temperature of 48 degrees and atarget relative humidity of 63 percent, in drier climates if a symmetricrelative humidity band is defined around the target humidity, e.g., ±2percent of 63 percent relative humidity, it will be likely that onaverage the aeration fan 13 will be activated during times of relativehumidity in the lower half of the humidity band, e.g., at relativehumidity between 61 and 63 percent. In that case, the actual temperatureand/or moisture content of the grain will be skewed away from the targeton the dry side, which is undesirable.

[0050] For this reason, aeration controller 14 may truncate the humidityband for dryer climates, such that for example, if the target relativehumidity is 63 percent, then the relative humidity band can be definedto be −1, +3 of that value, i.e., 62 to 66 percent. In other words, thehumidity band can be made non-symmetric about the target humidity. Inparticular, for dry climates, the relative humidity band around thetarget relative humidity can be truncated to increase the wet side ofthe band relative to the dry side of the band. Such techniques cangreatly improve aeration in extreme climates. Drier climates may be morelikely to have a temperature of 48 degrees and a relative humidity belowthe target of 63 percent. Truncating the humidity band to account forsuch climate-specific phenomena can improve the quality of aeration,thereby creating a greater likelihood of achieving the actual targetmoisture content for the grain. Moreover, truncation can be particularlyhelpful to compensate for micro-climate phenomena, such as local climateeffects of lakes, rivers, forests, or the like.

[0051] Truncation may occur automatically at aeration controller 14,based on measured climate conditions during previous aeration. In otherwords, band truncation can be an adaptive feature implemented byaeration controller 14. For example, aeration controller 14 may truncatethe humidity band to the wet side, based on measured dry conditionsduring earlier operation of aeration fan 13, or may truncate thehumidity band to the dry side, based on measured wet conditions duringearlier operation of aeration fan 13. Alternatively, truncation mayoccur via programmed variables submitted by an aeration expert atcentral computer 20, which is described in greater detail below. In anycase, the extent of extreme climate conditions required to initiate anadaptive truncation of the humidity band is subject to a wide variety ofimplementation-specific values.

[0052] The truncation feature may also be incorporated to improveaeration in wetter climates. In that case, aeration controller 14 maytruncate the humidity band for wetter climates, such that for example,if the target relative humidity is 63 percent, then the relativehumidity band can be defined to be −3, +1 of that value, i.e., 60 to 64percent. In other words, for wet climates, the relative humidity bandaround the target relative humidity can be truncated to increase the dryside of the band relative to the wet side of the band.

[0053] Aeration controller 14 may be programmed to initially truncatethe temperature or relative humidity bands, or may be programmed to onlytruncate the bands in response to a band adjustment event, such as whenthe backlog exceeds the backlog threshold. Moreover, aeration controller14 may receive feedback of the conditions during which aeration fan 13has operated, and may adjust and truncate the band(s) based on theprevious conditions in order to more adequately achieve the targettemperature and moisture content for the stored grain. In any case,improved aeration can be achieved in a climate specific manner. Thelevel of truncation may vary in different implementations. Adaptivetruncation may provide responsive adaptation of the aeration, which canimprove aeration in extreme climates, and can adjust for microclimatefluctuations as they occur.

[0054] In accordance with the principles of the invention, system 10also includes a central computer 20 that may define or control theoperation specific parameters of the respective aeration controllers 14.Central computer 20 can also log the information collected by sensors 16as well as the amount of time aeration fans 13 operate, the respectivebacklogs, the climate conditions during aeration fan operation times,and even the grain temperatures associated with the stored grain in therespective storage facilities 10.

[0055] Central computer 20 and aeration controllers 14 may operate in amaster-slave relationship, in which aeration controllers 14 provideinformation to central computer 20 in response to requests from centralcomputer 20. Requests for accumulated aeration data may occurperiodically, e.g., daily, hourly, or the like. Optionally, system 10may also support an alarm condition override in which a given controller14 is able to communicate to central computer 20 without being queried.Such an alarm condition to override the master-slave communicationprotocol can be effective in alerting central computer 20 of problems ordevice malfunctions associated with a given storage facility 12.

[0056] Central computer 20 can provide improved control and custodialcare of the aeration of stored grain. Farmers, or other agriculturalproducers, cooperatives, or companies may purchase the aeration serviceat a cost proportionate to the amount of stored grain to be aerated andthe duration of storage. In this manner, the purchaser of the aerationservice can avoid relatively high fixed costs that can be associatedwith various aeration hardware such as aeration controller 14. Inaddition, the seller of the service can control and meter the usage ofthe grain aeration technology.

[0057] Central computer 20 may provide the input parameters to thedifferent aeration controllers 14. The input parameters may include thetype of grain, the target temperature, the target moisture content, thesize of the temperature and relative humidity bands, the amount andtiming of truncation, if desired, the size of the aeration budget, thebacklog threshold, and any changes that should occur in response toovercoming the backlog threshold. In some cases, one or more of theseinput variables may be defined by an operation mode selected for arespective aeration controller 14. In any case, the input variables canbe defined differently for various different aeration controllers so asto account for different types of grains, different climates ormicroclimates, or other variables that may distinguish the operation ofaeration fans at different facilities. In some cases, input can beprovided in the form of objectives, e.g., desired moisture content and atarget delivery date.

[0058] The use of central computer 20 to accomplish the programming ofinput variables and/or mode selection, that would otherwise requireonsite attention, can improve aeration significantly and reduce costsassociated therewith. In particular, travel to on-site locations can beavoided, training of service persons can be reduced, and a moreknowledgeable person operating the central computer 20 can set parametersettings. In some embodiments, the operation of central computerrelative to controllers 14 can be automated as well, eliminating humanerror.

[0059] Also, central computer 20 can improve aeration by providingbetter quality control of the aeration. For example, central computer 20may facilitate the ability to recognize sensor malfunctions by comparingsensed ambient conditions of one facility 12 to those of anotherfacility in close geographic proximity, e.g., at the same site. Uponidentifying possible malfunctions, replacement parts or service may beprovided more quickly, which can further improve aeration services.

[0060] Central computer 20 may also log the various parameters, settingsand measurements accumulated by the respective aeration controller 14.Historical logs may provide a number of advantages. For example, ambientcondition sensor data may provide extensive history of weather trends.Accordingly, such information may be useful to weather centers or otheragencies concerned with weather prediction and trends. Also, thehistorical logs may provide useful backup, if for example, a givenaeration controller 14 malfunctions or is destroyed. In that case, aftera replacement aeration controller is installed, the history of aeration,backlog and other variables needed to continue the aeration in the samemanner as prior to the failure can be downloaded to the new aerationcontroller. Accordingly, historical logs on central computer can improvethe robustness of system 10 in the event of a device failure.

[0061] Logs stored on central computer 20 may also enable the ability totrack and verify the history of a lot of grain. In other words, logs oncentral computer 20 may be maintained for both aeration controllerspecific tracking purposes, and also grain specific tracking purposes.If a log of grain is moved from one facility to the next, the grainspecific log may track the lot of grain to provide a history of itstemperature and moisture content. In that case, a download ofinformation from the central computer 20 which it received from thefirst aeration controller that originally controlled the grain can bemade to the second aeration controller that subsequently controls thegrain. Moreover, networked grain aeration system 10 can facilitate thisdata transfer without requiring on-site attention.

[0062] In one implementation of the invention, a chain of custody isautomatically documented over time by the networked aeration system andstored in central computer 20. The documentation can even be downloaded,for example, to delivery vehicles, when the stored grain is moved from agiven storage facility. The information may be uploaded from the givenaeration controller 14 to the delivery vehicle, or downloaded from thecentral computer 20 to the delivery vehicle. In either case, the centralcomputer 20 can log the current location and track the grain to improveaccountability and trace ability.

[0063] Purchasers of the grain may desire information describing thehistory of a particular lot of grain being purchased. By allowing thisinformation to be downloaded from central computer 20 , purchasers canbe more readily assured of the aeration history and chain of custody ofthe grain. This data, in turn, can provide a better assurance of safetyand quality of the purchased grain. In some cases, grain given the stampof approval of the aeration service provider may demand a premium price.

[0064] Historical tracking and verification of grain can further providethe ability to demand premium prices, for example, for grain that wassystematically maintained in only high-quality settings in terms oftemperature and relative humidity for the life of the grain.Furthermore, centralized control and robust aeration management may alsoprovide the ability to insure against grain spoilage. For example, withcentralized control and robust monitoring capabilities, the custodian orsome other entity may be able to offer grain spoilage insurance tofarmers that own the allotments of grain, e.g., on the condition thatthe grain aeration control services are used. With the ability todefine, monitor and update aeration via centralized computer, thecustodian can better ensure that spoilage will not occur, and thereforecan be better positioned to provide grain spoilage insurance at anaffordable price.

[0065] One or more client computers 21A and 21B may also becommunicatively coupled to the central computer 20, such as via network18. Using client computers 21A and 21B, farmers or other purchasers ofthe aeration service may access information relating to their grain andthe aeration service provided for that grain. Each individual clientcomputer 21 may have access only to the data that pertains to thatparticular client, i.e., the purchaser of the service. In other words, afirst client computer 21A may not have access to data pertaining to asecond agricultural crop storage facility 12N, and likewise the secondclient computer 21N may not have access to data pertaining to the firstagricultural crop storage facility 12A. A password access function maybe used to gain access to the data, e.g., via a web browser interface.In addition, more sophisticated security and authentication protocolscan be employed.

[0066] In some embodiments, customers may be able to select aerationobjectives for their grain. For example, using client computer 21, thecustomer may be able to select a desired moisture content and a desireddelivery date. Central computer may receive the user input selectingaeration objectives, and may program the appropriate aeration controller14 so as to achieve the objectives. If a delivery date is selected, theaeration can be made to occur over time in a manner that achieves thedesired moisture content at that delivery date. Also, if a deliverylocation is defined, the aeration may be defined to purposely dry (wet)the grain in a manner commensurate with an amount of wetting (drying)that would predictably occur during grain delivery. For example, if thegrain is to be shipped across the ocean, aeration can be adjusted topurposely dry the grain, knowing that wetting will occur duringshipment.

[0067] Network 18 may comprise a packet based network such as theInternet, or a smaller public or private packet based network.Alternatively, network 18 may comprise a public switch telephone network(PSTN), or any other network sufficient to transfer information betweenthe aeration controllers 14 and central computer 20 and the variousclient computers 21 and central computer 20. Various levels of security,such as fire walls or virtual private networks (VPNs), may also beimplemented to ensure that information transferred through network 18 issecure.

[0068] As mentioned above, various other modifications could also bemade to aeration controllers 14 to improve aeration. For example, inaccordance with the principles of the invention, one particular variablethat could be taken into account by a respective aeration controller 14is heat produced by the respective aeration fan 13. For example,aeration fans 13 can give off heat from the motor, or more notably,aeration fans 13 may generate significant amounts of heat via frictionbetween the fan blades and the air. In either case, the heat produced byoperation of aeration fans 13 may blur the relationship between theambient temperature measurements by sensors 16 and the actualtemperature of air that will be forced into the facility upon activationof an aeration fan 13. Accordingly, an aeration method or algorithmexecuted by aeration controller 14 may account for heat produced by theaeration fan to yield better aeration results.

[0069] In one case, an aeration method executed in aeration controller14 makes a theoretical adjustment to sensed conditions by accounting forfan size and the size of the grain storage facility. For example, giventhe fan size and the size of the grain storage facility, a theoreticaloffset to sensed conditions can be calculated. This offset may beprogrammed into aeration controller 14, such as via a communication fromcentral computer 20 to the aeration controller 14. In any case, theoffset can account for heat produced by the fan, and can be used to moreaccurately define the actual air temperature or humidity that will beintroduced to the storage facility upon operation of the aeration fan13. In this manner, improved control of the conditions within the grainstorage facility can be achieved. The offset may be determinedexperimentally or mathematically. In either case, the offset may be usedto adjust measured ambient temperature to provide a better estimate ofthe actual temperature of air introduced by aeration fan 13. Moreover,the offset may be used to adjust the target temperature defined byaeration controller 14, e.g., to adjust the twenty-one day movingaverage of ambient temperature to compensate for the offset caused byheat production of aeration fan 13. Adjusting the target temperaturebased on heat produced by aeration fan 13 will likewise causetemperature band adjustment in a manner that accounts for heatproduction of aeration fan 13.

[0070] Additionally, a method executed in aeration controller 14 mayalso account for static pressure within the facility (specifically, forexample, at the location of an aeration fan or the entry point of airinto the grain). For example, the amount of static pressure may berelated to how full the facility is, relative to its capacity. Byaccounting for static pressure, a better approximation of the offset canbe achieved because the heat generated from the friction on the fanblade may be higher if static pressure is higher and may be lower ifstatic pressure is lower.

[0071] In one particular case, a feedback sensor, e.g., a feedback node(f-node) described in greater detail below, is used to measure theactual temperature and possibly relative humidity (RH) of air after ithas gone through the fan. The f-node may also sense static pressure, ifdesired. The use of the f-node can achieve an actual measurement of theoffset, which can then be used as feedback to the aeration controller14. The aeration controller 14 can then adjust the operation of theaeration fan 13 accordingly.

[0072] Also, modified air-conditions measured by the feedback sensor canbe used to define a more useful target temperature and target relativehumidity for the bands. In other words, the target temperature andtarget relative humidity may be adjusted based on feedback measurementsof actual conditions within a facility. One or more feedback nodes maybe positioned after the aeration fan 13 but prior to the stored grain,e.g., in the plenum. Also, feedback nodes may be positioned in theexhaust of a crop storage facility 12, or in different strata of thegrain to provide a number of storage measurements.

[0073] System 10 may also be configured to log and record the data ofthe f-node to provide data demonstrating the actual conditions withinthe storage facility over time. In other words, the data from an f-nodemay be logged by central computer 20 for later examination or use. Forexample, such f-node data could be used as documentation to demonstratethat the grain inside the storage facility was never exposed toconditions favorable or susceptible to the growth of microbes includingfungus that can produce mycotoxins, allergens, or other contaminants.This documentation, in turn, could increase the value of the grain andjustify the added cost of an f-node sensor. Recording actual conditionsinside the storage facility during aeration may also occur in the eventof manual override during which an aeration fan is turned on manuallyon-site. Information defining conditions during manual override may beused later to adjust aeration in order to improve aeration results interms of achieving a target temperature and moisture content. In thismanner, centralized monitoring can improve accountability of theaeration because manual overrides are documented and subsequently usedto adjust the aeration, as needed, to achieve the desired temperatureand moisture content.

[0074]FIG. 2 is a conceptual diagram of an agricultural storage facilitymaking use of a networked grain aeration system. In this example, theagricultural storage facility comprises a grain bin 22 that stores grain23. Grain bin 22 is fitted with an aeration fan 13 that is controlled byaeration controller 14. Aeration controller 14 comprises a computercontroller that controls operation of aeration fan 13 according to anaeration algorithm such as those described in U.S. Pat. No. 4,688,332 or4,522,335. Additionally, aeration controller 14 may execute moreadvanced aeration techniques described herein, such as techniques thatutilize feedback sensor 29 to further improve the quality of aeration.Also, aeration controller 14 may execute aeration techniques thatutilize truncated temperature or relative humidity bands to improveaeration for climate specific scenarios as outlined herein. Furthermore,the truncation feature can be an adaptive feature of aeration controller14 such that temperature bands or relative humidity bands used to defineaeration fan operation times can be adjusted based on previousconditions during which the aeration fan has operated. Heaters, misters,or other grain conditioning devices (not shown) may also be controlledby aeration controller 14.

[0075] Aeration controller 14 may be coupled to a computer network 18.In this manner, as outlined above, the sensed information collected byaeration controller 14 and operation of aeration fan 13 can be centrallylogged and monitored by a central computer (not shown in FIG. 2). Clientcomputers connected to network 18 may also gain client-specific accessto such information.

[0076] In operation, temperature sensor 26 measures ambient temperatureand provides the measurement of ambient temperature to aerationcontroller 14. Similarly, relative humidity sensor 27 measures ambientrelative humidity and provides the measurement of relative humidity toaeration controller 14. Sensors 26 and 27 may comprise separatecomponents or an integrated sensor that provides sensing functionalityfor both temperature and relative humidity. Temperature sensor 28measures the temperature of stored grain 23 and provides the measurementto aeration controller 14. In addition, a barometric pressure sensor maybe used by aeration controller 14 to adjust a target relative humidityfor a given air temperature. Barometric pressure measurements used toadjust a target relative humidity for a given air temperature can beparticularly useful to compensate for elevation of the storage site,relative to sea level.

[0077] Aeration controller 14 can be programmed with input specifying adesired temperature and moisture content for the stored grain. Aerationcontroller 14 may define a temperature band and a relative humidity bandrespectively around a target temperature and a target relative humiditythat corresponds to the desired moisture content for a giventemperature. The target temperature may be selected based on a desiredtemperature, or based on a desired temperature relative to the currenttemperature of grain 23. In one example, the target temperature isdefined by a twenty-one day moving average of ambient temperature. Inany case, a temperature band can be defined about the targettemperature, and a relative humidity band can be defined about a targetrelative humidity, which may be temperature dependent. The size of thebands may vary widely in different implementations.

[0078] If sensor 26 identifies an ambient temperature within the definedtemperature band, say 47 degrees, aeration controller 14 identifies thetarget relative humidity associated with the 47 degree temperature, say63 percent. The target relative humidity may be dependent on the currentambient temperature, and may also be dependent on the currenttemperature of grain 23, e.g., dependent on the ambient temperaturerelative to the temperature of grain 23. Aeration controller 14 mayaccess a lookup table in memory (not shown) or it may calculate frompsychometric formulas to identify the target relative humidity given anambient temperature and possibly a current grain temperature. In anycase, if relative humidity sensor 27 measures a relative humidity withinthe relative humidity band of the target relative humidity, say 61percent to 65 percent (±2 percent of 63 percent), then aerationcontroller 14 may activate aeration fan 13. A control node (not shown inFIG. 2) may be used to execute fan activation in response to controlsignals sent from aeration controller 14.

[0079] A feedback sensor 29 may also be used to measure a temperatureoffset caused by heat production associated with aeration fan 13. Heatfrom aeration fan 13 may offset the temperature of air introduced tograin bin 22 (as illustrated by the arrows) away from the ambienttemperature measured by temperature sensor 26. Accordingly, feedbacksensor 29 can be used to provide a more accurate temperature measurementonce fan 13 is turned on. The offset measured by feedback sensor 29 canbe used to adjust the aeration accordingly. Additionally oralternatively, the measurements of feedback senor 29 may be used toprovide actual measurements of temperature and/or relative humidityintroduced to grain bin 22. Such information may be logged by centralcomputer 20 (FIG. 1) to provide a more accurate history of the aerationof grain 23.

[0080] Alternatively, rather than implement a feedback sensor 29, theheat produced by fan 13 may be accounted for by a theoretical orexperimentally determined offset value, which may be used to adjust themeasured ambient temperature during execution of the aeration algorithm.In this manner, heat produced by fan 13 may not undermine theeffectiveness of aeration. Instead, the temperature band used byaeration controller 14 (as outlined above) may be defined around anambient temperature measured by temperature sensor 26 plus thetheoretical offset. A measurement of static pressure may be used in thegeneration of the theoretical offset. Additionally, the temperatureband, or the relative humidity band may be truncated as described hereinto improve aeration for climate specific scenarios.

[0081] If desired, additional feedback sensors may also be positioned atvarious locations of grain bin 22. For example, one or more feedbacksensors may be positioned after the aeration fan 13 but prior to thestored grain, e.g., in the plenum. Also, feedback sensors may bepositioned in the exhaust of a crop storage facility 12, or in differentstrata of grain 23 to provide a number of storage measurements.

[0082] Aeration controller 14 may also implement a regulator-likemechanism that ensures that the aeration fain 13 can only run for anallotted amount of time, on average, which can conserve power and avoidunnecessary aeration. For example, aeration controller 14 may budget anamount of time for a given time interval, say four hours per day.Aeration controller 14 may also accumulate a backlog of time to accountfor unused time that was budgeted for aeration. Thus, if the desiredconditions were not present for two days, then twelve hours ofaccumulated budget may be used on the third day. In other words, thefour hour budgets for three days may accumulate to twelve hours, whichcan be used in succession once the desired conditions occur. Once theaccumulation of budgeted time is used, aeration fan 13 may be turned offeven if the desired ambient conditions are still present.

[0083] In addition, aeration controller 14 may define a backlogthreshold, say twenty hours (the equivalent of five days at four hoursof budget per day). If the backlog exceeds the threshold, aerationcontroller may enlarge the temperature and/or relative humidity bands toimprove the likelihood that aeration will occur. This can help ensurethat at least some aeration occurs even if the ambient conditions aresub-optimal.

[0084] Also, as described above, aeration controller 14 may implementaeration techniques in which truncation of the temperature and/orrelative humidity bands are performed to improve aeration for climatespecific scenarios. In particular, aeration controller 14 may truncatethe temperature and/or relative humidity bands for different climatescenarios in a manner that causes aeration to achieve improved resultsin terms of achieving a target temperature and/or moisture content. Thetruncated band(s) may be predefined for a known climate, or may beadaptively altered by aeration controller 14 based on the actual climatemeasured during the times when aeration fan 13 operates. In one example,adaptive truncation of a relative humidity band based on actual climatemeasured during the times when aeration fan 13 has operated may be anadvanced operation mode of aeration controller 14, that can be selectedor enabled by central computer 20.

[0085] Aeration controller 14 may truncate the humidity band for dryerclimates, such that for example, if the target relative humidity is 63percent, then the relative humidity band can be defined to be −1, +3 ofthat value, i.e., 62 to 66 percent. In other words, the humidity bandcan be made non-symmetric about the target humidity. Such techniques cangreatly improve aeration in extreme climates. Similarly, the truncationfeature may also be incorporated to improve aeration in wetter climates.In that case, aeration controller 14 may truncate the humidity band forwetter climates, such that for example, if the target relative humidityis 63 percent, then the relative humidity band can be defined to be −3,+1 of that value, i.e., 60 to 64 percent. Again, the level of truncationmay vary in different implementations.

[0086] Moreover, as mentioned, the truncation can be an adaptive featurethat changes based on measured conditions during operation of aerationfan 13. For example, the relative humidity band may originally besymmetric about a target. In particular, given a target of 63 percent,the relative humidity band can be defined to be −2, +2 of that value,i.e., 61 to 65 percent. Thereafter, if operation of the aeration fan 13primarily occurs at periods of time during which measured relativehumidity is in the dry side of the band, i.e., between 61 and 63percent, then aeration controller may adaptively truncate the humidityband to enlarge the wet side of the band and decrease the dry side ofthe band.

[0087] In other words, if aeration controller 14 can determine thatoperation of the aeration fan 13 has primarily occurred at periods oftime during which measured relative humidity is in the dry side of theband. In that case, aeration controller 14 can modify the band to favoroperation during wetter periods of time, e.g., the band can beadaptively changed to be −1, +3 of the 63 percent target, i.e., 62 to 66percent. Aeration controller 14 may continue to modify and adaptivelyalter the bands as aeration occurs in different weather. In some cases,the relative humidity band may be originally defined symmetrically aboutthe target relative humidity, then truncated to the wet side after fanoperation in dry conditions, then re-established in a symmetric bandafter the truncation compensates for the previous dry conditions, andthen possibly truncated to the wet side, e.g., if subsequent fanoperation occurs during extended wet conditions.

[0088] In this manner, adaptive truncation of the relative humidity bandcan achieve improved results in terms of achieving a target moisturecontent for the stored grain. In other words, adaptive truncation ofclimate bands can cause grain can be aerated in a manner that improvesthe ability to achieve desired grain conditions. Threshold values forclimate parameters defined during operation of the aeration fan 13 canbe used to define when such adaptive truncation should occur, and aresubject to a wide variety of implementations.

[0089] Moreover, centralized control and monitoring of grain aerationcan also improve the level of aeration quality, allowing the provider ofthe aeration service to centrally monitor whether the individualaeration controllers 14 are working properly. Another advantage ofnetworked grain aeration includes the ability to provide more effectiveaeration control among various grain storage units. In other words,instead of a local grain storage manager controlling aeration as he orshe sees fit, central expertise can be used to monitor and moreeffectively control aeration.

[0090] Networked grain aeration may also allow for a new and inventivepricing arrangement that can be attractive to prospective purchasers. Inparticular, fees may be charged in amounts commensurate to an amount ofgrain being stored in any given agricultural crop storage facility. Theduration of storage can also be reflected in the price. Such a pricingscheme can reduce fixed costs to individual farmers and improve thelikelihood of industry acceptance of such services. Such a pricingscheme may also overcome a “free-rider” problem, wherein a purchaser ofan aeration unit for a small storage facility uses the aeration unit ina much larger facility or for multiple facilities.

[0091] The results achieved by a free-rider may not be particularlygreat aeration results, but they may be nevertheless better aerationresults than would be achieved with no aeration control. Still, becausethe free-rider often makes use of improperly sized aeration fans inoversized storage facilities, free-riders may undermine consumerconfidence in an aeration control product or service. In other words,prospective customers may view the results achieved by free-riders asinadequate and correlate inadequacy with the seller of the product. Infact, however, the free-riders may not be achieving the most effectiveresults. Thus, avoiding the free-rider problem may improve good willassociated with the seller of the aeration product or service, inaddition to forcing the free-rider to bear a more proportionate cost.

[0092] Centralized monitoring of aeration may also allow the selling ofgrain spoilage insurance for an amount of grain being stored in anygiven agricultural crop storage facility. In other words, networkedgrain aeration can facilitate the ability to guarantee against grainspoilage. Farmers may be able to take out loans from a bank, based onthe amount of harvested crops that the farmer owns but has not yet sold,but such loans may be conditioned on the purchase of spoilage insurance.The seller of aeration services, utilizing networked grain aerationhaving centralized control, may be able to provide this insurancebecause the centralized control allows the seller of the service toadequately manage against grain spoilage. In particular, the use ofnetworked grain aeration can reduce insurance premiums to an affordablelevel.

[0093]FIG. 3 is an exemplary block diagram of one embodiment of grainaeration system that can be installed in at a storage facility. Asillustrated aeration controller 14 can be communicatively coupled to acentral computer. In any case, aeration controller 14 controls operationof aeration fan 13, and possibly other grain management tools such asheaters, misters, or the like, based on sensed conditions.

[0094] Aeration controller 14 may also be coupled to a memory device 32,which can be used to store programmed aeration parameters, recentaeration data prior to transmission to central computer 20, look-uptables, and possibly computer readable instructions (software) that canbe executed by aeration controller 14 to perform the aeration techniquesdescribed herein. Memory 32 may also store programmable identificationnumbers associated with aeration controller 14 and its various nodes. Anindication of storage capacity and current usage may also be stored.

[0095] If desired, aeration controller 14 may also be coupled to a userinterface (not shown) to provide on-site control and programmingcapabilities. The user interface may be used by on-site personal toaccess local aeration data, operational parameters, operational modes,and the like. The user interface may also be used to manually overridecentralized control, for example, to turn on the aeration fan. Suchmanual overrides, however, can be reported to central computer 20 sothat future aeration can account for and possibly adjust aerationbecause of the manual override. The user interface may take the form ofa browser application executing in a microprocessor, such as deployed ina laptop computer or a personal digital assistant (PDA) with wirelesscommunication capabilities. The user interface can be programmed toissue commands to controller 14.

[0096] As shown in FIG. 3, aeration controller 14 is coupled to one ormore nodes, such as, for example, c-node 31, w-node 32, s-node 33,t-node 34, i-node 35, and f-node 36. The nodes correspond to varioussensors, switches, or other units used by aeration controller 14 duringaeration. Aeration controller 14 and respective nodes 31-36 may operateaccording to a master slave relationship in which aeration controller 14polls nodes 31-36 to obtain sensed information, and instructs nodes31-36, for example, when activation of aeration fan 13 should occur.

[0097] C-node 31 may correspond to an on/off relay switch used to turnaeration fan 13 on and off. Similar nodes may also be used for heaters,misters, or the like. C-node 31 may also have a static pressure gaugesensor. In any case, c-node 31 can be used to switch aeration fan 13 onand off, at appropriate times identified by aeration controller 14. Forexample, aeration controller 14 may issue control signals to the c-nodeto cause aeration fan 13 to be switched on or off.

[0098] W-node 32 may be a weather node used to sense one or more ambientconditions surrounding the given storage facility. For example, w-node32 may include temperature sensor, a relative humidity sensor, abarometric pressure sensor, a rain gauge, a global positioning system(GPS) module, and possibly a wind speed/direction sensor.

[0099] F-node 36 may include a temperature sensor and a relativehumidity sensor. F-node 36 may be used to provide feedback to aerationcontroller 14 as outlined above. By way of example, one or more f-nodesmay be positioned after the aeration fan 13 but prior to the storedgrain, e.g., in the plenum. Also, one or more f-nodes may be positionedin the exhaust of a crop storage facility 12, or in different strata ofthe grain to provide a number of grain storage measurements.

[0100] T-node 34 may provide an interface to an external thermocouplemodule, which can be used to measure temperatures within a grain storagebin. In other words, T-node 34 may correspond to a temperature sensorpositioned to measure the current temperature of stored grain. T-node 34may or may not also include a relative humidity sensor.

[0101] S-node 33 may provide an interface to an external electronicscale module, used to weigh shipments of grain as they are brought infor storage. Accordingly, s-node can be used by aeration controller 14to identify the amount of grain storage in the given storage facility.As mentioned, memory 32 may store both an indication of storage capacityand current storage usage. Such information may be determined by s-node33. The amount of grain being aerated may affect pricing, in accordancewith one or more of the pricing schemes described herein.

[0102] I-node 35 may provide current metering capability by using acurrent transformer and rectifier circuit. Thus, i-node 35 can be usedto measure electricity use, and to document information related toelectricity use. Such information may be stored locally by aerationcontroller and then transferred to central computer 20. Power suppliersmay desire collective estimations of electricity usage associated with anumber of facilities that use the aeration systems. In this manner,power usage of the fans controlled by the networked grain aerationsystem may merit special rates. If electricity supplied to a grainstorage site is subject to demand charges, the controllers may rotatefan usage so as to avoid these demand charges.

[0103]FIG. 4 is a flow diagram according to one embodiment of theinvention. As shown, aeration controllers 14 are used to controlaeration fans according to sensed conditions (41). Moreover, a centralcomputer 20 can be communicatively coupled to the aeration controllers14 to monitor aeration (42). The custodian of the service can chargefees to customers based on the amount of grain being aerated and theduration of the storage (43). In this manner, customers may be moreaccepting of the aeration service because fixed costs associated withaeration hardware can be eliminated as a fixed expense to the customer.

[0104]FIG. 5 is another flow diagram according to one embodiment of theinvention. Again, aeration controllers 14 are used to control aerationfans according to sensed conditions (51), and a central computer 20 canbe communicatively coupled to the aeration controllers 14 to remotelymonitor aeration (52). The custodian of the service can sell grainspoilage insurance (53) because the centralized control allows for thecontrol needed to ensure against spoilage. In particular, centralizedcontrol of aeration can help keep premiums affordable, e.g., based onthe condition that the aeration service is used.

[0105]FIG. 6 is another flow diagram according to one embodiment of theinvention. Again, aeration controllers 14 are used to control aerationfans according to sensed conditions (61), and a central computer 20 canbe communicatively coupled to the aeration controllers 14 to remotelymonitor aeration (62). Central computer 20 can store aeration data (63),such as data pertaining to aeration fan operation, ambient conditions(or f-node conditions) during aeration, and various operationalparameters associated with the aeration controllers 14. Accordingly, ifan aeration controller 14 fails and is replaced (64), the aeration datacan be downloaded to the new aeration controller (65) to ensure thataeration will continue in a manner consistent with that prior to thefailure.

[0106]FIG. 7 is another flow diagram according to one embodiment of theinvention. Again, aeration controllers 14 are used to control aerationfans according to sensed conditions (71), and a central computer 20 canbe communicatively coupled to the aeration controllers 14 to remotelymonitor aeration (72). Predictable aeration results can be modeled forprospective customers to identify to the prospective customer, the valueof the system (73).

[0107]FIG. 8 is another flow diagram according to one embodiment of theinvention. Again, aeration controllers 14 are used to control aerationfans according to sensed conditions (81), and a central computer 20 canbe communicatively coupled to the aeration controllers 14 to remotelymonitor aeration (82). As grain is moved (83), a chain of custody canalso be recorded (84) to provide quality assurances to prospective grainpurchasers. Such assurances can result in premium prices for thedocumented grain.

[0108]FIG. 9 is a flow diagram illustrating an aeration technique thatmay be used as part of a networked grain aeration system or a moreconventional non-networked grain aeration unit. As shown, aerationcontroller 14 defines truncated temperature and/or relative humiditybands in order to improve aeration for extreme climate scenarios (91).Aeration controller 14 may also define an aeration budget (92), andaccumulate a backlog when budgeted aeration time is not used.Eventually, when the ambient conditions fall within the truncated bands,aeration controller 14 can activate aeration fan 13 in order to aeratethe grain (94). Importantly, the truncation of the temperature and/orhumidity bands can result in aeration that attains improved aerationresults in terms of achieving a target temperature and/or targetmoisture content.

[0109]FIG. 10 is another flow diagram according to one embodiment of theinvention. As shown aeration controller 14 defines climate bands such asa temperature band and a relative humidity band (101). For example, thebands may be programmed about target values, or may be defined about atarget determined as a function of current grain temperature. Therelative humidity band may be temperature dependent, and may further bedependent on the temperature of the stored grain relative to ambienttemperature.

[0110] Aeration controller 14 causes aeration fan 13 to aerate the grainwhen the local conditions fall inside the defined climate bands (102).Moreover, aeration controller 14 thereafter adaptively adjusts one ormore of the climate bands in a truncated manner (103). In other words,if aeration has primarily occurred for more than a defined amount oftime during wet conditions, e.g., conditions falling on the wetter sideof the relative humidity band, aeration controller 14 can truncate therelative humidity band to the dry side. Similarly, if aeration hasprimarily occurred for more than a defined amount of time during dryconditions, e.g., conditions falling on the dryer side of the relativehumidity band, aeration controller can truncate the relative humidityband to the wet side.

[0111] Then, when more aeration is desired (yes branch of 104), aerationcontroller 14 causes aeration fan 13 to aerate the grain when the localconditions fall inside the truncated climate bands (102). In thismanner, truncation of the climate bands, including the relative humidityband or the temperature band can be an adaptive feature of aerationcontroller 14 that improves the ability to achieve a target temperatureand/or moisture content for the stored grain. Adaptive truncation ofclimate bands during aeration may be enabled on aeration controller 14by selecting a specific operation mode that corresponds to thetruncation feature. Moreover, mode selection can be made offsite atcentral computer 20, if a networked grain aeration control system isemployed.

[0112]FIG. 11 is another flow diagram according to one embodiment of theinvention. As shown aeration controller 14 defines an aeration budget(111). For example, the budget may be a programmed value or inputprovided to aeration controller 14 that defines the maximum amount ofoperation time of aeration fan 13 per unit time, e.g., four hours perday.

[0113] Aeration controller 14 also defines climate bands such as atemperature band and a relative humidity band (112). Again, the bandsmay be programmed about target values, or may be defined about a targetdetermined as a function of current grain temperature. The relativehumidity band may be temperature dependent, and may further be dependenton the temperature of the stored grain relative to ambient temperature.

[0114] One or more sensors 16 such as those described above measure theconditions surrounding the storage facility 12 (113). Aerationcontroller 14 polls the sensors 16 to obtain sensed data, and makes adetermination whether to aerate the grain based on the sensed conditions(114). In particular, to perform aeration (yes branch of 114), aerationcontroller 14 causes aeration fan 13 to aerate the grain, such as byinvoking a control node (c-node) to switch aeration fan 13 on.

[0115] If aeration does not occur (no branch of 114), then the unusedportion of the aeration budget is backlogged (115). For example aerationmay be regulated by aeration controller 14 such that aeration occursonly when there is remaining aeration budget unused in the backlog. Inother words, if four hours per day are allocated, then four hours can beused each day. If some time is unused in a given day, that time isbacklogged so that it can be used during subsequent days when thedesired conditions are present. Thus, if aeration does not occur on thefirst day, but does occur on the second day, eight hours of aeration mayoccur in succession on the second day, i.e., four hours of budget forthe second day plus four hours of backlog from the first day.

[0116] Furthermore, when more aeration is desired (no branch of 116),aeration controller 14 may redefine the bands, such as by adaptivelytruncating the bands as described above. Aeration may be stopped (yesbranch of 116) by manually overriding aeration controller 14. Forexample, once the grain is sold and removed from facility 12, theaeration controller 14 may be powered down or otherwise disabled.

[0117]FIG. 12 is another flow diagram according to one embodiment of theinvention. As shown, aeration controller identifies an offset associatedwith operation of aeration fan 13 (121). For example, the offset may beidentified by a programmed theoretical offset value, or may be measuredby a feed back sensor 29. In either case, aeration controller 14accounts for the offset during grain aeration (122). In this manner,changes to the air introduced by aeration fan 13 from the sensed ambientconditions, such as a slight temperature increase, will not reduce theeffectiveness of aeration. Instead, the offset can be used by aerationcontroller 14 to adjust operation of the aeration fan 13 accordingly toaccount for heat production or other effects caused by the operation ofaeration fan 13.

[0118] Aeration is an important part of modem agricultural management.In particular, aeration can be effective in avoiding spoilage of grain,preserving grain weight, minimizing insect infestation, improvingmoisture content, re-hydrating grain, avoiding cracking of kernels,reducing stress cracks, and generally preserving and possibly improvingthe quality of stored grains. The techniques described herein canimprove grain aeration and the aeration service.

[0119] Many implementations and embodiments of the invention have beendescribed. For instance, may different features of a networked grainaeration system have been described. In addition other features andmethods have been described which may be used in a networked grainaeration system, or a more conventional non-networked aeration controlsystem. Nevertheless, it is understood that various modifications can bemade without departing from the spirit and scope of the invention. Forexample, the invention may use only some of the many features describedabove. Furthermore, other nodes are envisioned, including nodes thatmeasure barometric pressure or other ambient conditions. Moreover, sometechniques, such as truncating the relative humidity and/or temperaturebands based on climate may be implemented in non-networked systems.Accordingly, other implementations and embodiments are within the scopeof the following claims.

1. A system comprising: a first controller coupled to a first sensor anda first aeration fan, the first sensor and the first aeration fan beingpositioned in proximity to a first agricultural crop storage facilitylocated at a first site, wherein the first controller controls theoperation of the first aeration fan according to conditions sensed bythe first sensor; a second controller coupled to a second sensor and asecond aeration fan, the second sensor and the second aeration fanpositioned in proximity to a second agricultural crop storage facilitylocated at a second site, wherein the second controller controls theoperation of the second aeration fan according to conditions sensed bythe second sensor; and a central computer communicatively coupled to thefirst and second controllers, wherein the central computer monitorsoperation of the first and second aeration fans.
 2. The system of claim1, wherein the central computer stores a log of operation timeassociated with the first and second aeration fans.
 3. The system ofclaim 1, wherein the central computer stores a log of conditions sensedby the first and second sensors.
 4. The system of claim 1, wherein theagricultural crop storage facilities include grain storage bins.
 5. Thesystem of claim 1, wherein the central computer is communicativelycoupled to the first and second controller via a packet based network.6. The system of claim 1, wherein the first and second controllers arecoupled to the first and second aeration fans via control nodes.
 7. Thesystem of claim 1, wherein the central computer stores first dataindicative of the conditions sensed by the sensors, and second dataindicative of the operation time associated with the aeration fans. 8.The system of claim 7, further comprising: a first client computercommunicatively coupled to the central computer, the first clientcomputer having access to data pertaining to the first agricultural cropstorage facility located at the first site; and a second client computercommunicative coupled to the central computer, the second clientcomputer having access to data pertaining to the second agriculturalcrop storage facility located at the second site.
 9. The system of claim8, wherein the first client computer does not have access to datapertaining to the second agricultural crop storage facility, and whereinthe second client computer does not have access to data pertaining tothe first agricultural crop storage facility.
 10. The system of claim 1,further comprising: a first set of sensors coupled to the firstcontroller, wherein the first controller controls the operation of thefirst aeration fan according to conditions sensed by the first set ofsensors; and a second set of sensors coupled to the second controller,wherein the second controller controls the operation of the secondaeration fan according to conditions sensed by the second set ofsensors.
 11. The system of claim 10, wherein the central computerselects operational modes for the first and second controllers, theoperational mode for the first controller defining operationalparameters for operation of the first aeration fan according toconditions sensed by the first set of sensors and the operational modefor the second controller defining operational parameters for operationof the second aeration fan according to conditions sensed by the secondset of sensors.
 12. The system of claim 11, wherein the operational modefor the first controller is different from the operational mode for thesecond controller.
 13. The system of claim 11, wherein the operationalmode for the first controller defines operational parameters including atemperature band and a temperature-dependent relative humidity band,wherein the first controller causes the first aeration fan to turn onwhen the ambient conditions sensed by the first set of sensors indicatethat ambient temperature is within the temperature band and ambientrelative humidity is within the temperature-dependent relative humidityband.
 14. The system of claim 13, wherein the operational parameters forthe first controller further include an amount of time that the firstaeration fan can operate per day, the amount of time accumulating into abacklog when the aeration fan does not operate, wherein the firstcontroller causes the first aeration fan to operate only when thebacklog has not been exhausted.
 15. The system of claim 14, wherein thefirst controller automatically adjusts the operational parameters byincreasing the temperature band and the temperature-dependent relativehumidity band when the backlog exceeds a backlog threshold.
 16. Thesystem of claim 13, wherein at least one of the temperature band and thetemperature-dependent relative humidity band is truncated such that thetruncated band is non-symmetric about a target value, the truncationbeing based on a climate surrounding the first agricultural crop storagefacility located at the first site.
 17. The system of claim 1, whereinthe first controller controls the operation of the first aeration fanaccording to ambient conditions sensed by the first sensor and heatproduced by the first aeration fan; and wherein the second controllercontrols the operation of the second aeration fan according to ambientconditions sensed by the second sensor and heat produced by the secondaeration fan.
 18. A method comprising: monitoring and regulatingaeration fans positioned in remotely located agricultural crop storagefacilities via a central computer of a networked grain aeration system;and charging fees in an amount related to an amount of grain andduration of storage being stored in each of the respective agriculturalcrop storage facilities.
 19. A method comprising: monitoring aerationfans positioned in remotely located agricultural crop storage facilitiesvia a central computer of a networked grain aeration system; controllingthe aeration fans; and selling grain spoilage insurance for amounts ofgrain being stored in one of the agricultural crop storage facilitiesassociated with the monitored aeration fans.
 20. A method comprising:monitoring aeration fans positioned in remotely located agriculturalcrop storage facilities via a central computer of a networked grainaeration system; and storing a history log of the aeration of grainstored in each of the remotely located agricultural crop storagefacilities.
 21. The method of claim 20, wherein storing the history logincludes storing information relating to operation times of the aerationfans.
 22. The method of claim 20, wherein storing the history logincludes storing information relating to ambient conditions sensed atthe remotely located agricultural storage crop facilities.
 23. Themethod of claim 20, further comprising: replacing an aeration controllerfor one of the aeration fans; and downloading information from thehistory log to the replaced aeration controller, the downloadedinformation including information relating to the operation time andambient conditions in proximity to an aeration fan associated with thereplaced aeration controller.
 24. A method comprising: monitoringaeration fans positioned in remotely located agricultural crop storagefacilities via a central computer of a networked grain aeration system;and automatically recording a chain of custody of grain stored in theremotely located agricultural crop storage facilities.
 25. The method ofclaim 24, further comprising storing a history log relating to theaeration during the recorded chain of custody.
 26. A method comprising:controlling operation of at least one aeration fan in an agriculturalcrop storage facility to provide aeration of grain based on graintemperature, ambient temperature and ambient relative humidity so as toapproach a target temperature and desired moisture content for thegrain; and adjusting operation of the aeration fan to account for heatcaused by operation of the fan.
 27. A method of aerating graincomprising: defining a temperature band around a target graintemperature; defining a relative humidity band around a target relativehumidity determined as a function of ambient temperature, the relativehumidity band being truncated as a function of climate, such that adryer portion of the band is larger in a wet climate and a wetterportion of the band is larger in a dry climate; defining a budgetedamount of aeration for a unit of time for the grain; accumulating abacklog of budgeted amounts of aeration with passing units of time whenaeration does not occur; and aerating the grain when the backlog definesunused budgeted time, an ambient temperature is within the temperatureband and an ambient relative humidity is within the relative humidityband.
 28. The method of claim 27, further comprising widening therelative humidity band when less than a predetermined amount of aerationhas occurred.
 29. The method of claim 27, further comprising adjustingthe relative humidity band in a non-symmetric fashion based on a pasthistory of relative humidity when aeration occurred.
 30. A method ofaerating grain comprising: defining a temperature band around a targetgrain temperature; defining a relative humidity band around a targetrelative humidity determined as a function of ambient temperature, therelative humidity band being truncated as a function of climate, suchthat a dryer portion of the band is larger in a wet climate and a wetterportion of the band is larger in a dry climate; defining a budgetedamount of aeration for a unit of time for the grain; accumulating abacklog of budgeted amounts of aeration with passing units of time whenaeration does not occur; aerating the grain when the backlog definesunused budgeted time, an ambient temperature is within the temperatureband and an ambient relative humidity is within the relative humidityband.
 31. A method comprising: defining a temperature band around atarget grain temperature; defining a relative humidity band around atarget relative humidity determined as a function of ambienttemperature; defining a budgeted amount of aeration for a unit of timefor an allotment of grain; accumulating a backlog of budgeted amounts ofaeration with passing units of time when aeration does not occur;aerating the allotment of grain when the backlog defines unused budgetedtime, an ambient temperature is within the temperature band and anambient relative humidity is within the relative humidity band; andadjusting the relative humidity band in a non-symmetric fashion aroundthe target relative humidity based on a past history of relativehumidity when aeration occurred.
 32. The method of claim 31, furthercomprising: adjusting the temperature band in a non-symmetric fashionaround the target temperature based on a past history of temperaturewhen aeration occurred.
 33. An aeration system for aerating stored grainat a grain storage facility comprising: an aeration fan; a controllerthat controls operation of the aeration fan according to climateconditions; and a sensor coupled to the computer controller to measureat least one climate condition, the sensor being positioned within thestorage facility in close proximity to the aeration fan such thatconditions measured by the sensor account for heat produced by theaeration fan.
 34. The aeration system of claim 33, the sensor being afirst sensor, the system further comprising a second sensor coupled tothe computer controller and positioned outside the grain storagefacility to measure an ambient climate condition, wherein the computercontroller determines an offset based on the conditions measured by thefirst sensor relative to the conditions measured by the second sensorand adjusts operation of the aeration fan based on the offset.
 35. Theaeration system of claim 33, further comprising a central computercommunicatively coupled to the controller and remotely located relativeto the grain storage facility, the central computer storing a historylog of conditions sensed by the sensor and operation time associatedwith the aeration fan.
 36. An aeration system for aerating stored grainat a grain storage facility comprising: means for defining a temperatureband around a target grain temperature; means for defining a relativehumidity band around a target relative humidity determined as a functionof ambient temperature, the relative humidity band being truncated as afunction of climate, such that a dryer portion of the band is larger ina wet climate and a wetter portion of the band is larger in a dryclimate; means for defining a budgeted amount of aeration for a unit oftime for the stored grain; means for accumulating a backlog of budgetedamounts of aeration with passing units of time when aeration does notoccur; and means for aerating the stored grain when the backlog definesunused budgeted time, an ambient temperature is within the temperatureband and an ambient relative humidity is within the relative humidityband.
 37. An aeration system for aerating stored grain at a grainstorage facility comprising: means for defining a temperature bandaround a target grain temperature; means for defining a relativehumidity band around a target relative humidity determined as a functionof ambient temperature; means for defining a budgeted amount of aerationfor a unit of time for the stored grain; means for accumulating abacklog of budgeted amounts of aeration with passing units of time whenaeration does not occur; means for aerating the stored grain when thebacklog defines unused budgeted time, an ambient temperature is withinthe temperature band and an ambient relative humidity is within therelative humidity band; and means for adjusting the relative humidityband in a non-symmetric fashion based on a past history of relativehumidity when aeration occurred.
 38. A method comprising: defining atemperature band around a target grain temperature; defining a relativehumidity band around a target relative humidity determined as a functionof ambient temperature; aerating grain when an ambient temperature iswithin the temperature band and an ambient relative humidity is withinthe relative humidity band; and adjusting the relative humidity bandaround the target relative humidity in a non-symmetric fashion based ona past history of ambient relative humidity when aeration occurred. 39.An aeration system for aerating stored grain at a grain storage facilitycomprising: at least one sensor to sense conditions; at least oneaeration fan; and a controller coupled to the aeration fan and thesensor, the controlled being configured to: define a temperature bandaround a target grain temperature; define a relative humidity bandaround a target relative humidity determined as a function of ambienttemperature; turn on the aeration fan to aerate the grain when a sensedambient temperature is within the temperature band and a sensed ambientrelative humidity is within the relative humidity band; and adjust therelative humidity band around the target relative humidity in anon-symmetric fashion based on a past history of sensed ambient relativehumidity when aeration occurred.
 40. A method comprising: monitoringaeration fans positioned in remotely located agricultural crop storagefacilities via a central computer of a networked grain aeration system;and controlling operation of the aeration fans based on electricitydemand in geographical locations associated with the agricultural cropstorage facilities.
 41. A system comprising: a first controller coupledto a first sensor and a first aeration fan, the first sensor and thefirst aeration fan being positioned in proximity to a first agriculturalcrop storage facility located at a first site, wherein the firstcontroller controls the operation of the first aeration fan according toconditions sensed by the first sensor; a second controller coupled to asecond sensor and a second aeration fan, the second sensor and thesecond aeration fan positioned in proximity to a second agriculturalcrop storage facility located at a second site, wherein the secondcontroller controls the operation of the second aeration fan accordingto conditions sensed by the second sensor; and a central computercommunicatively coupled to the first and second controllers, wherein thecentral computer monitors operation of the first and second aerationfans and selects operational modes for the first and second controllers,the operational mode for the first controller defining operationalparameters for operation of the first aeration fan according toconditions sensed by the first set of sensors and the operational modefor the second controller defining operational parameters for operationof the second aeration fan according to conditions sensed by the secondset of sensors, wherein the operational modes for the controllers defineoperational parameters including temperature bands andtemperature-dependent relative humidity bands, wherein at least one ofthe temperature bands and the temperature-dependent relative humiditybands are truncated such that the truncated bands are non-symmetricabout target values, the truncation being based on climates surroundingthe respective agricultural crop storage facility.